A simple method for control of lactate accumulation in suspension cultures of Chinese hamster ovary (CHO) cells based on the culture's pH was developed. When glucose levels in culture reach a low level (generally below 1 mM) cells begin to take up lactic acid from the culture medium resulting in a rise in pH. A nutrient feeding method has been optimized which delivers a concentrated glucose solution triggered by rising pH. We have shown that this high-end pH-controlled delivery of glucose can dramatically reduce or eliminate the accumulation of lactate during the growth phase of a fed-batch CHO cell culture at both bench scale and large scale (2,500 L). This method has proven applicable to the majority of CHO cell lines producing monoclonal antibodies and other therapeutic proteins. Using this technology to enhance a 12-day fed-batch process that already incorporated very high initial cell densities and highly concentrated medium and feeds resulted in an approximate doubling of the final titers for eight cell lines. The increase in titer was due to additional cell growth and higher cell specific productivity.

A simple method originally designed to control lactate accumulation in fed-batch cultures of Chinese Hamster Ovary (CHO) cells has been modified and extended to allow cells in culture to control their own rate of perfusion to precisely deliver nutritional requirements. The method allows for very fast expansion of cells to high density while using a minimal volume of concentrated perfusion medium. When the short-duration cell-controlled perfusion is performed in the production bioreactor and is immediately followed by a conventional fed-batch culture using highly concentrated feeds, the overall productivity of the culture is approximately doubled when compared with a highly optimized state-of-the-art fed-batch process. The technology was applied with near uniform success to five CHO cell processes producing five different humanized monoclonal antibodies. The increases in productivity were due to the increases in sustained viable cell densities. Biotechnol. Bioeng. 2017;114: 1438-1447. © 2017 Wiley Periodicals, Inc.

In order to address the increasing demand for biologics, cell culture intensification using perfusion offers significantly higher productivities while also reducing manufacturing costs, especially when part of an integrated, continuous bioprocess. An initial study of a long‐duration perfusion process using a cell‐bleed to maintain a target cell density observed a 2.1‐fold higher cell‐specific productivity and a gradual decline in the culture growth rate when perfused at an overall lower rate. Subsequent studies sought an alternative process that largely reduced the overall volume of media needed by first perfusing at a high cell‐specific perfusion rate (CSPR) to support a high cell density followed by continued perfusion at a low CSPR to promote a more productive stationary phase. This high intensity, low‐volume perfusion (HILVOP) process achieved cumulative volumetric productivities of 1.5–1.6 g/L/day with two CHO cell lines. When compared to each cell line's respective commercial‐ready, fed‐batch process, a 3.1–3.8‐fold productivity increase was demonstrated while yielding similar product quality. Furthermore, the higher productivity achieved with HILVOP used 6.6–12.3‐fold less media than a similarly productive long‐duration process. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 34:1472–1481, 2018